I have thought about a bruteforce method to flatten a deeply nested list with Data::Dumper, by massaging the output of Data::Dumper. It doesn't have any recursion (at least not in my perl script), and all that's needed is a simple regular expression to strip out unwanted stuff. I have quickly wrote the follow code to prove that it can be done. Forget about the performance of this method, it's just a proof of concept. :-)

#!/usr/local/bin/perl -w
use strict;
use Data::Dumper;

my @arr = ([1,2],[3,4,[5,6]],7);

my $list = flatten(\@arr);
print Dumper($list);

sub flatten
{
    my $data = Dumper(shift);
    $data =~ s/(\$\w+\s+=\s+)|[\n\[\];]//gm; # massage the output
    return [eval "$data"];
}
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And the output is as expected -

$VAR1 = [
          1,
          2,
          3,
          4,
          5,
          6,
          7
        ];
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